JPH0619304A - Developing device - Google Patents

Abstract

PURPOSE:To prevent developer from being biased in a developer carrying path because of the change of the posture and the direction of a developing device. CONSTITUTION:The device is provided with a hopper 21 storing and supplying the developer, a photosensitive body 1 carrying the developer from the hopper 21 and forming a developing field 23 around the photosensitive body 1, the developer carrying path 22 returning the developer through another path after supplying the developer to the photosensitive body 1 at a part along a recovering roller 25 through a developer supply port 61 and circularly carrying the developer, and a developer carrying body 24 provided in the path 22 so as to carry the developer; and the path 22 is made a closed space including the carrying body 24 together with the photosensitive body 1 and the roller 25, and a developer play space 55 between the photosensitive body 1 and the roller 25 in the closed space and the carrying body 24 in the path 22 facing the body 1 and the roller 25 through the supply port 61 is set within magnetic field 54 having strength by which the developer is held against gravity by magnets 53 and 81 arranged around the space 55.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus having the same, and more particularly to a developing device used in a copying machine or a laser beam printer for forming an image by an electrophotographic method.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 3-101784 and Japanese Unexamined Patent Publication No. 3-28248 disclose a developing device of this type.

The one disclosed in the former publication is provided with a hopper for storing toner behind a developing sleeve adjacent to the photosensitive drum. Then, the toner in the hopper is agitated by the toner agitator, and the toner is agitated toward the toner supply port provided on the side of the developing sleeve of the hopper, and the toner is supplied to the developing sleeve through the toner supply port.

The developing sleeve carries the supplied toner on the surface thereof, and after the layer thickness of the toner is regulated by the pressing of the elastic blade, the developing sleeve is made to face the surface of the photosensitive drum after image exposure, and the surface of the photosensitive drum. Develops the electrostatic latent image carried by the image exposure with toner.

The photosensitive drum and the image forming elements around the photosensitive drum are made into cartridges which are attachable to and detachable from the main body of the image forming apparatus, which is advantageous for maintenance.

In the latter publication, a circulation conveyance path for circulating and conveying the developer is provided behind the developing sleeve. One of the forward path and the return path of the circulation conveyance path is along the developing sleeve, and the toner replenishment path from the hopper provided at the back is connected to a part of the other path.

In the circulation conveyance path, a two-component developer containing a carrier and toner is circulated and conveyed while being agitated by a developer conveyance screw, and is supplied to the developing sleeve at a portion facing the development sleeve. The developing sleeve conveys the carried developer to a portion facing the photosensitive drum and supplies toner to the developing sleeve to perform development.

The circulation conveyance path is an open passage which is opened at the portion facing the developing sleeve and communicates with a wide space on the developing sleeve side.

[0009]

By the way, recently, it has been widely practiced to make a developing device, a photosensitive drum including the developing device, and an image forming element around the developing device into a cartridge as disclosed in the rear of the former. It is being appreciated.

The posture of the cartridge taken out from the main body is unknown. For example, the axis of the developing sleeve may be oriented vertically, or the upper portion of the developing device may be oriented laterally or downward.

On the other hand, while the image forming apparatus is being downsized, the handling direction is not constant and the developing device may be in various directions as described above.

It is also desired that the image forming apparatus can be installed in a plurality of postures depending on the size of the image forming apparatus and its widespread use in personal use, depending on the state of the vacant space, the surrounding equipment and the working environment. In this case, the change of the installation posture causes a change in the posture of the developing device.

When the orientation of the developing device is not constant in handling or in use as described above, in the developing devices described in the above publications, the developer is biased.

For example, in the former publication, the developer in the hopper and around the developing sleeve can move freely, so if the axis of the developing sleeve is inclined or becomes vertical, Is biased to the lower side by the action of gravity.

Therefore, if this is a temporary handling, it is necessary to mount the developing device in an appropriate posture and to drive it for a while so that the developer is evenly distributed.

Therefore, useless waiting time is required.

Further, in the case of continuous use in which the installation orientation of the main body is selected, the unevenness of the developer cannot be eliminated, and the development performance is not constant depending on the installation orientation selection. In some cases, poor development or failure of development may occur.

In the latter publication described above, a screw having a good trapping property of the developer is adopted as a developer carrier in the circulation carrier path for circulating and carrying the developer. However, the portion of the circulation conveyance path facing the developing sleeve is entirely open to a wide space around the developing sleeve.

Therefore, between the screw and the developing sleeve in this portion, a large developer play space is formed in which the developer, which is not exerted by the catching force or the carrying force of the screw and the developing sleeve, can be freely formed. Is biased toward the lower side in accordance with the change in the attitude of the developing device, and the same problem occurs in the above case.

The present invention provides a developing device which can prevent the developer in the developer conveying path from being biased due to the change of the attitude and the direction of the developing device and solve the above-mentioned conventional problems. Is an issue.

[0021]

In order to achieve the above-mentioned object, the present invention has a hopper that stores and supplies a developer, and a developer from the hopper that conveys the developer to a developing field around the photoconductor. After supplying the developer to the developer carrier through the developer supply port in a portion along the developer carrier that forms, a developer transport path for returning the developer by another route and circulating and transporting the developer, A developer transport body provided in the developer transport path for transporting the developer, and the developer transport path is a closed space including the developer carrier together with the developer carrier.
A magnet arranged around the developer play space between the developer carrying body and the developer carrying body in the developer carrying path facing the developer carrying body in the closed space. It is characterized in that the developer is set within a magnetic field range of a strength capable of holding the developer against gravity.

The developer carrier is preferably a screw, and the closed space preferably has an inner surface close to the outer diameter of the screw.

Further, it can be set such that at least a portion of the developer transport path where the developer supply port is provided has an outer diameter inner space of the screw located in the magnetic field.

The magnet may be provided on the developer carrying member, or may be provided on the outer periphery of the developer carrying path for holding the developer.

The developer carrier is made of a magnetic material, and the direction of rotation of the developer carrier, which is opposed to the developer carrier through the developer supply port, is set such that the peripheral surface facing the developer carrier is from the bottom to the top. It is better to move to.

[0026]

According to the above construction of the present invention, the developer from the hopper is circulated by the developer carrier along the developer carrier path containing the developer while the developer carrier is along the developer carrier. Part of the developer can be supplied to the developing field through the developer supply port during the circulating transportation to perform development, and the developer transportation path is a closed space including the developer carrying body and the developer carrying body. Therefore, the developer being circulated and conveyed can be easily trapped in each part during conveyance to regulate free movement, and the developer carrier in the closed space and the surface through the developer supply port The developer play space created between the developer transport path and the developer transport body is set within the magnetic field range of the strength that can hold the developer by the magnets placed around it against gravity. Yes, the developer located in the developer play space is Although it is difficult for the developing sleeve to be caught or carried by the developing sleeve, since the developer has magnetism, it is held against the gravity by the magnetic field and loses its degree of freedom and becomes stable. It is possible to prevent the developer inside from being biased by the influence of gravity.

When the developer transport body is a screw, the developer in the developer transport path can be easily captured, and the closed space formed by the developer transport path has an inner surface close to the outer diameter of the screw. With this configuration, the developer can be easily captured by the developer transport body over the entire closed space, and the free movement of the developer can be regulated to prevent the bias even more advantageously.

If the screw inner diameter space of at least the portion of the developer conveying path where the developer supply port is provided is located within the magnetic field, in addition to the trapping of the developer by the screw. Since the magnetic field is also held by the magnetic field, the bias of the developer can be more surely prevented.

If the developer carrying member has a magnet, it can also serve as a cylindrical magnet built in the developing sleeve.

When the magnet is provided around the outer periphery of the developer transport path and holds the developer, the magnetic field of the developer can be held at any portion.

When the developer transport body is a magnetic body, a magnetic circuit is connected between the magnet and the magnet, and the magnetic field for holding the developer by the limited magnet is likely to reach the entire developer transport path.

When the direction of rotation of the developer carrier, which is opposed to the developer carrier through the developer supply port, is the direction in which the peripheral surface facing the developer carrier moves upward from below, the developer carrier is carried. The developer conveyed by the developer conveying body facing the body is scraped up on the side opposite to the developer carrying body to make it bulky. Therefore, a sufficient amount of developer can be collected on the surface of the developer carrying body with a small amount of developer. Can be contacted with.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention shown in FIGS. 1 to 7 will be described below.

1 to 5 show a developing device, and FIG. 6 shows an image forming device equipped with the developing device. FIG. 7 shows in detail the structure around the photosensitive drum of the image forming apparatus.

This embodiment is a simple, small and inexpensive image forming apparatus particularly suitable for personal use such as being connected to a personal computer. As shown in FIG. The case of a printer having 1 and a print head 2 for performing image exposure on the printer 1 is illustrated.

The print head 2 employs a so-called solid scanning system in which light emitting elements such as LEDs and a liquid crystal shutter are arranged to perform image exposure. Larger models can also employ a printhead that deflects the laser beam to perform scanning.

As shown in FIG.
As shown in FIG. 3, the charging charger 3, the print head 2, the developing device 4, the transfer roller 5, and the cleaning device 6 are sequentially arranged in the rotation direction of the photosensitive drum 1 as indicated by the arrow.

Returning to FIG. 6, in front of the transfer section between the photosensitive drum 1 and the transfer roller 5, a paper feed path 13 is provided which is connected to a manual paper feed port 12 on the outer surface of the main body 11, Behind the transfer section, a fixing device 18 provided in the main body 11
A transport path 15 to is provided.

Behind the fixing device 18, a paper discharge path 17 communicating with the paper discharge port 16 on the outer surface of the main body 11 is provided.

The main body 11 has rectangular side surfaces on the front and rear sides as viewed in a direction perpendicular to the plane of the paper, has two installation surfaces 11a and 11b along one long side and one short side, and the other side has the short side. A mouth 12 and a paper exit 16 are provided. Therefore, installation surface 11
Paper can be fed and discharged regardless of whether the main body 11 is installed by either a or 11b.

Further, with respect to the photosensitive drum 1, the cleaning device 6 is located on the side opposite to the installation surface 11a, and the developing device 4 is located on the installation surface 11a side. The transfer roller 5 is located on the side facing the opening 16.

The paper feed port 12 is provided near the installation surface 11a on the outer surface of the main body 11, and the paper ejection port 16 is provided on the installation surface 11a.
It is provided near the end on the side far from a.

A fixing device 18 is provided at a position apart from the photosensitive drum 1 near the sheet discharge port 16 side between the sheet discharge port 16 and the transfer portion.

As a result, the recording sheet fed from the sheet feeding port 12 is sent to the transfer portion, and after the transfer, the fixing device 18
The sheet can be discharged to the sheet discharge port 16 through the short path using a very small space in the main body 11.

The fixing device 18 is located on the photosensitive drum 1 regardless of which of the installation surfaces 11a and 11b the main body 11 is installed on. Therefore, it is possible to prevent the heat of the fixing device 18 from adversely affecting the image forming mechanism portion around the photosensitive drum 1.

Further, the developing device 4 has the installation surface 11 in view of the above arrangement.
Whether the main body 11 is installed by either a or 11b,
It will be located on the side or below the photosensitive drum 1. For this reason, it is possible to prevent the developer from being excessively supplied due to the gravitational action and clogging the respective parts when the developer is supplied to the photosensitive drum 1 as a developer carrying body to which the developer is directly supplied from the developing device 4. Can be, especially the photosensitive drum 1
This is effective for the developing method of the present embodiment in which the developer is brought into contact with a wide area of the above to temporarily develop the entire surface and then the developer in the non-image area is removed and collected.

Further, even if the developer leaks from the developing device 4, it is avoided that the developer adheres to the photosensitive drum 1 and stains it.

The paper passage path and the transfer portion of the main body 11 can be opened and closed for jam clearance, repair, and the like. In this case
So that the right side portion of the developing device 4 in is opened,
The developing device 4 and the photosensitive drum 1 which are unitized can be attached and detached through the opening in the direction indicated by an arrow 31 in the figure.

The attaching / detaching direction can be freely set according to the arrangement of other devices and the opening / closing structure of each part of the main body 11.

The developing device 4 itself is shown in detail in FIGS. This will be described. A hopper 21 that stores and supplies the developer, a developer transport path 22 that transports the developer from the hopper 21, and a developer that transports the developer on the developer transport path 22 along the developer transport path 22. Developer carrier 2 that supplies developer to the photosensitive drum 1 as a carrier
4 is provided so that development can be performed in the developing field 23 around the photosensitive drum 1.

The developer transport path 22 includes a forward path 22a for sending the developer from the hopper and a continuous path 22b for returning the developer sent to the forward path 22a to the hopper 21. It forms a circuit. A part of the outward route 22a and the return route 22b, that is, the outward route 22a in this embodiment.
A wide developer supply port 61 is provided at a, which is in contact with the photosensitive drum 1 as the developer carrying member and supplies a sufficient amount of the developer to the entire surface development.

As a result, the water is stored in the hopper 21,
The developer stirred by the stirring blade 20 is sent to the forward path 22a of the developer transport path 22, and then the return path 22 is continued.
Since the returning to the inside of the hopper 21 through b is repeated, a fixed amount of the developer is constantly circulated and conveyed in the circulation path formed by the forward path 22a and the return path 22b of the hopper 21 and the developer conveyance path 22 while the developer is in the hopper 21. It is possible to stably supply the developer to the photosensitive drum 1 as the developer carrying member through the developer supply port 61 during the circulation and conveyance so that proper development can be performed.

In the development of the system in this embodiment, the developer is supplied to a relatively wide area of the photoconductor drum 1 through the wide developer supply port 61, and the image area and the non-image area on the photoconductor drum 1 are exposed. The entire surface development in which both the image areas are developed by the developer suction force to the photosensitive drum 1 side due to the potential difference or the magnetic action is once performed. When utilizing the magnetic force, a magnetic developer is used.

Next, when the entire surface developing portion on the photosensitive drum 1 reaches the developing field 23, it is attracted to the non-image portion on the photosensitive drum 1 by the developer suction force to the developing sleeve 25 side due to the potential difference and the magnetic action. The developing agent is sucked onto the developing sleeve 25 and removed to complete the development.

When the developer in the non-image area is removed by suction, when an alternating suction force due to an AC potential or the like is applied between the photosensitive drum 1 and the developing sleeve 25, the developer is adsorbed particularly on the surface of the non-image area. Even a stable developer, the relatively free or free enough developer particles in the upper layer of the non-image area are vibrated first to collide with the stable developer. , The developing sleeve 25 can be effectively sucked and removed.

The developer on the developing sleeve 25 removed from the non-image portion is returned to and collected in the developer conveying path 22 by the rotation of the developing sleeve 25. Reference numeral 52 denotes a blade for this recovery, and also serves as a seal for preventing the developer from leaking between the developer supply port 61 and the developing sleeve 25.

Further, the developer which is circulated and conveyed returns to the inside of the hopper 21 every time it is circulated, and is renewed and mixed with the developer inside the hopper 21, so that the entire development including the developer inside the hopper 21 is performed. The developer can be supplied while being kept homogeneous, and stable development can be guaranteed without sudden deterioration due to abnormal consumption of some components or uneven distribution of the developer with a long history of use.

Since the forward path 22a and the return path 22b are closed spaces containing the developer transport body 24, the developing device 4 can be used alone or with the main body 11 with the developing device 4 pulled out. Even if the installation direction is changed, the developer in each part in the developer transport path 22 is held in place against the gravity effect between the developer transport body 24 and the developer transport body 24. Also, it is possible to avoid biasing to one side of the return path.

Further, the developer supply port 61, which is in contact with the developer carrying member such as the photosensitive drum 1 of the developer transport path 22, has the forward path 22a.
In the developing system, the developer carrying path 22 can be installed along the photosensitive drum 1 and the developing sleeve 25 with a small bulk because the developing method is partially in contact with the developing sleeve 25.

Further, in this case, if the developer conveying path 22 forms the closed space together with the photosensitive drum 1 and the developing sleeve 25, the closed space required for supplying the developer to the developing field 23 is narrow. Therefore, the developer can be held more reliably.

The developing sleeve 25 is installed in a developing field cover 30a formed integrally with a part of the developing casing 30 forming the hopper 21 and the developer transport path 22.

Further, in the closed space, the developer conveying body 24 in the forward path 22a, the photosensitive drum 1 and the developing sleeve 2 are provided.
5 side, the developer play space 55, which does not reach the carrying force of the developer carrying body 24, and does not carry the photosensitive drum 1 and the developing sleeve 25, is provided in the developing sleeve 25 and the photosensitive drum 1. It is set so as to be positioned in a magnetic field 54 which is formed between the magnetic poles of the cylindrical magnet 53 and the sector magnet 81 provided inside and which has a strength capable of holding the developer against gravity.

Therefore, the developer in the developer play space 55 is hard to be caught on the spot without receiving the carrying force of the developer carrying body 24 and the carrying force of the photosensitive drum 1 and the developing sleeve 25, but it is magnetized. If so, the magnetic field 54 holds it against gravity, so that the bias of the developer can be prevented more reliably.

The developer carrying capacity in the developer carrying path 22 is
By increasing the lead of the screw blade 24a of the developer carrier 24, which is a screw, the size is appropriately increased toward the downstream side from the outlet 21a of the hopper 21 to the inlet 21b of the hopper 21 via the forward path 22a and the return path 22b. Is set to.

As a result, a greater conveying force is exerted on the developer sent from the hopper 21 toward the downstream side, and the developer forward path 22a and the developer forward path 22b.
The margin in the inside is gradually increased, and finally, it is sent into the hopper 21 having a large capacity to be released, so that the developer may be clogged during circulatory transfer, and the density becomes close to this, and the development is performed. It is possible to prevent the agent from being strongly fatigued.

If the lead of the developer transport body 24 becomes large, the gripping force of the developer becomes weak, and the developer cannot be sufficiently held in each part, and the bias may not be prevented.

In this case, it is possible to take measures by forming the screw blade 24a in multiple lines.

Further, the width of the connecting path 22c from the outward path 22a to the returning path 22b is made larger than that of the outward path 22a, and the developer being circulated and conveyed is loosened in this portion, so that the next transition in the curved path is made. And transportation becomes smooth.

Further, since the developer carrier 24 in the outward path 22a is a screw and faces the hopper 21, the free developer in the hopper 21 can be well captured and reliably delivered.

The developer carrying capacity of the developer carrying body 24 can be appropriately set by the diameter of the other developer carrying body and the driving speed.

The developer carrying capacity of the hopper outlet 21a is set to be larger than that of the developing sleeve 25 of the developer carrier 24. Therefore, it is possible to prevent the supply amount of the developer from being insufficient to be supplied to the developing field 23 while being circulated and conveyed.

In this embodiment, the lead of the portion of the developer carrying body 24 facing the photosensitive drum 1 is fixed.
As a result, the developer supplied to the photoconductor drum 1 while being circulated and conveyed is different from the photoconductor drum 1 due to the difference in the conveyance speed.
It is possible to prevent the supply amount to the non-uniformity.

When the developer transport body 24 on the return path 22b side has largely entered the hopper 21 as in the present embodiment, the developer is transferred from the return path 22b into the hopper 21 to return the developer to the inside of the hopper 21. It is possible to positively agitate and mix with the developer in the hopper 21 while surely feeding the developer into the inner part of the hopper 21.

Each developer carrier 24 is driven to rotate in the opposite direction by the drive mechanism 82 by the lead of the same direction, and the developer is carried by the meshing of the gears 27 and 28 directly connected to each other. Can be achieved, and the structure of the drive mechanism 82 can be simplified.

Further, this gear connection is performed via the torque limiter 57. Therefore, in the unlikely event of the outward route 22a or the return route 2
Even if excessive addition occurs due to clogging of the developer or high density in 2b, it can be dealt with by the slip of the torque limiter 57,
Avoid excessive driving.

Replenishing port 21 for replenishing the developer of hopper 21
A cover 58 is provided on c, and the developer supply container 43 is attached to remove the cover 58 so that the developer can be supplied.

Since the hopper 21 is located outside one end in the longitudinal direction of the photosensitive drum 1 and the forward path 22a and the return path 22b extend from the hopper 21 in parallel with the photosensitive drum 1, the hopper 21 is located outside the photosensitive drum 1. Not located around the radial surface,
Since only the outward path 22a and the inward path 22b of the developer are located around the outer diameter surface of the photosensitive drum 1 and in parallel with it, the developer can be supplied to the developing sleeve 25. The space occupying can be halved.

Therefore, it is advantageous for further downsizing of the image forming section, and there is a space for image exposure, installation of charging means, etc., and the degree of freedom in installation of the image forming device increases. Further, the developing device 4 itself can be installed in any orientation.

Further, in the case where the developing device 4 is unitized with the photosensitive drum 1 and the like and is attached to and detached from the main body 11 in a lateral direction perpendicular to the axis of the photosensitive drum 1 as shown by an arrow 31 in FIGS. In the case where the hopper is at the back of the developer transport path 22 as described above, the hopper 21 interferes with the print head 2 so that the attachment / detachment cannot be performed.

Therefore, it may be considered that the print head 2 is also handled as a unit together with the developing device 4 and the photosensitive drum 1 and is simultaneously attached / detached. However, the print head 2 is expensive and there is a problem in treating it as a consumable item as a part of the detachable unit.

When the hopper 21 is located outside one end in the longitudinal direction of the photosensitive drum 1 as in this embodiment, it does not interfere with the print head 2 when attaching and detaching, so that the print head 2 is used as an element on the main body 11 side. There is an advantage that it can be fixed.

The cleaning device 6 has a cleaning blade 32 in contact with the surface of the photosensitive drum 1, and the cleaning blade 32 removes the residual developer after transfer from the surface of the photosensitive drum 1.

The cleaning blade 32 is provided at one edge of the developer receiving port 34 of the developer returning path 33 for returning the removed residual developer to the hopper 21, and the removed residual developer is supplied to the developer returning path 33. It is designed to be scooped into. Reference numeral 56 is a seal piece provided on the other edge of the developer receiving port 34.

The developer returning passage 33 is provided with a developer conveying body 35 which is a screw, and returns the residual developer received in the developer returning passage 33 into the hopper 21.
A special device for storing and discarding the residual developer removed by this is unnecessary.

If the image forming apparatus of the present embodiment is of a small size suitable for personal use, the residual developer is collected and used again, but the amount is small and a large amount in the hopper 21. Since it is used by being mixed with the developer of No. 1 by stirring, it is difficult to exert any influence and it does not cause any particular problem.

In this embodiment, the forward path 22a and the backward path 22b of the developer transport path 22 are the forward path 22a facing the photosensitive drum 1 in the installation direction of the main body 11 installed on the installation surface 11a shown in FIG. Is located slightly higher than the return path 22b.

As a result, even when the main body 11 is installed on the installation surface 11b, the positional relationship between the outward path 22a and the return path 22b becomes constant. Therefore, the supply state of the developer is unlikely to change regardless of whether the main body 11 is installed on the installation surfaces 11a and 11b, and in both cases, the developer is supplied to the photosensitive drum 1 from below. It is advantageous to prevent excessive supply due to gravity.

Therefore, it is possible to prevent the developer from being strongly stressed due to a high density state or clogging due to excessive supply.

It should be noted that the forward path 22a and the return path 22b may be arranged in a different positional relationship. As a result, the outward path 22a is on the lower side, so that the developer at the lowest position in the hopper 21 can be sent out and used for development.

The developer transport body 35 is the developer transport path 22.
Are located in parallel to the developer transport body 24 and close to each other with the photosensitive drum 1 sandwiched therebetween, and can be easily driven by gear-linking and interlocking with them, which contributes to simplification and downsizing of the apparatus. Contribute.

The stirring blade 20 is interlocked with the developer carrier 24 via gears 41 and 42 to rotate.

With this, without any special drive source or operation,
The developer hopper 21 can be smoothly transferred to the developer transport path 22.

As the developer carrying members 24, 35, various known ones such as those having a carrying blade can be adopted other than the screw.

Particularly, as the developer transport body 35, since the developer transport amount is extremely small, a simple one such as a coil spring can be adopted.

FIG. 8 shows a second embodiment of the present invention, in which the developer supply port 61 provided in the outward path 22a of the developer transport path 22 is formed to have a narrow width, and development is performed on the development sleeve 25 which is a developer carrying member. It is of a conventional type in which a developing agent is supplied to supply the agent.

The layer thickness of the developer supplied to the developing sleeve 25 is regulated by the elastic blade 51, and when the developer is charged by the friction at this time and conveyed to the developing field 23, the image portion on the photosensitive drum 1 is imaged. It is sucked into and developed.

The developer in the developer play space 55 can be held against gravity by the magnetic field 54 formed between the magnetic poles of the cylindrical magnet 53 in the developing sleeve 25.
Reference numeral 50 is a seal piece that seals between the developing field cover 30a and the developing sleeve 25.

Since the other structure is the same as that of the first embodiment, the description is omitted.

[0099]

According to the present invention, while the developer from the hopper is circulated and conveyed along the developer conveying path containing the developer by the developer conveying body, the portion of the developer conveying path along the developer carrying body. At, it is possible to perform the development by supplying the developer in the middle of the circulation conveyance to the developing field through the developer supply port,
The developer transport path is a closed space that encloses the developer transport body together with the developer carrier, and it is easy to regulate the free movement by capturing the developer being circulated and transported at each part during transport, A magnet disposed around a developer play space formed in the closed space between the developer carrier and the developer carrier in the developer transport path facing the developer carrier through the developer carrier. The developer located in the developer play space is hard to be caught or carried by the developer carrier and the developing sleeve, because the developer is set within the magnetic field range of the strength capable of holding the developer against gravity. Since the developer has magnetism, it is held against the gravity by the magnetic field and loses its degree of freedom to stabilize, so that the developer in the developer transport path is affected by gravity even if the attitude of the developing device changes. It is possible to prevent the Can have orientation and installation direction is changed without affecting the developing performance, it takes the subsequent break-operation, it is possible to avoid that cause the state of development failure and development impossible.

When the developer transport body is a screw, the developer in the developer transport path can be easily captured, and the closed space formed by the developer transport path has an inner surface close to the outer diameter of the screw. With this configuration, the developer can be easily captured by the developer transporter in the entire closed space, and the free movement of the developer can be regulated to further advantageously prevent the bias and contribute to the stability of the developing performance.

If the outer diameter inner space of the screw of at least the portion where the developer supply port is provided in the developer transport path is set to be located in the magnetic field, in addition to the trapping of the developer by the screw. Since it is held by the magnetic field, the bias of the developer can be more surely prevented and the developing performance can be further stabilized.

When the developer carrying member is provided with a magnet, it can be used also as a cylindrical magnet or the like built in the developing sleeve, and the structure is not complicated and the cost does not increase.

When the magnet is provided around the outer periphery of the developer transport path for holding the developer, the magnetic field of the developer can be satisfied at any portion, and the handling orientation or the installation orientation changes. It is possible to achieve the required stable development performance.

When the screw is a magnetic material, a magnetic circuit is connected between the magnet and the magnet, and a magnetic field for holding the developer is easily exerted by the limited magnet over the entire conveying path of the developer, so that the developing performance is high and stable. The sex can be easily obtained.

When the direction of rotation of the developer carrier, which is opposed to the developer carrier through the developer supply port, is the direction in which the peripheral surface facing the developer carrier moves upward from below, the developer carrier is carried out. The developer conveyed by the developer conveying body facing the body is scraped up on the side opposite to the developer carrying body to make it bulky. Therefore, a sufficient amount of developer can be collected on the surface of the developer carrying body with a small amount of developer. Therefore, it is possible to reduce the required amount of the developer to be conveyed and to reduce the size of the apparatus and prevent the developer from fatigue.

[Brief description of drawings]

FIG. 1 is a perspective view of a developing device as a first embodiment to which the present invention is applied.

FIG. 2 is a plan view of the developing device of FIG. 1 as seen in a horizontal cross section.

FIG. 3 is a plan view showing a part of the developing device of FIG. 1 on a hopper side.

FIG. 4 is a sectional view of a hopper portion of the developing device of FIG.

5 is a cross-sectional view of a part of the developing device of FIG. 1 on the hopper side as viewed in a vertical direction.

FIG. 6 is an overall schematic configuration diagram of an image forming apparatus having the developing device of FIG.

7 is a cross-sectional view showing an image forming unit of the image forming apparatus in FIG.

FIG. 8 is a sectional view showing an image forming unit of an image forming apparatus equipped with a developing device as a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 4 Developing device 21 Hopper 22 Developer transport path 22a Forward path 22b Return path 23 Development field 24 Developer transport body 25 Developing sleeve 53 Magnet roller 54 Magnetic field 55 Developer play space 71 Magnet 61 Developer supply port

[Procedure amendment]

[Submission date] January 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title of the invention Developing device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus having the same, and more particularly to a developing device used in a copying machine or a laser beam printer for forming an image by an electrophotographic method.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 3-101784 and Japanese Unexamined Patent Publication No. 3-28248 disclose a developing device of this type.

The one disclosed in the former publication is provided with a hopper for storing toner behind a developing sleeve adjacent to the photosensitive drum. Then, the toner in the hopper is agitated by the toner agitator, and the toner is agitated toward the toner supply port provided on the side of the developing sleeve of the hopper, and the toner is supplied to the developing sleeve through the toner supply port.

The developing sleeve carries the supplied toner on the surface thereof, and after the layer thickness of the toner is regulated by the pressing of the elastic blade, the developing sleeve is made to face the surface of the photosensitive drum after image exposure, and the surface of the photosensitive drum. Develops the electrostatic latent image carried by the image exposure with toner.

The photosensitive drum and the image forming elements around the photosensitive drum are made into cartridges which are attachable to and detachable from the main body of the image forming apparatus, which is advantageous for maintenance.

In the latter publication, a circulation conveyance path for circulating and conveying the developer is provided behind the developing sleeve. One of the forward path and the return path of the circulation conveyance path is along the developing sleeve, and the toner replenishment path from the hopper provided at the back is connected to a part of the other path.

In the circulation conveyance path, a two-component developer containing a carrier and toner is circulated and conveyed while being agitated by a developer conveyance screw, and is supplied to the developing sleeve at a portion facing the development sleeve. The developing sleeve conveys the carried developer to a portion facing the photosensitive drum and supplies toner to the developing sleeve to perform development.

The circulation conveyance path is an open passage which is opened at the portion facing the developing sleeve and communicates with a wide space on the developing sleeve side.

[0009]

By the way, recently, it has been widely practiced to make a developing device, a photosensitive drum including the developing device, and an image forming element around the developing device into a cartridge as disclosed in the rear of the former. It is being appreciated.

The posture of the cartridge taken out from the main body is unknown. For example, the axis of the developing sleeve may be oriented vertically, or the upper portion of the developing device may be oriented laterally or downward.

On the other hand, while the image forming apparatus is being downsized, the handling direction is not constant and the developing device may be in various directions as described above.

It is also desired that the image forming apparatus can be installed in a plurality of postures depending on the size of the image forming apparatus and its widespread use in personal use, depending on the state of the vacant space, the surrounding equipment and the working environment. In this case, the change of the installation posture causes a change in the posture of the developing device.

When the orientation of the developing device is not constant in handling or in use as described above, in the developing devices described in the above publications, the developer is biased.

For example, in the former publication, the developer in the hopper and around the developing sleeve can move freely, so if the axis of the developing sleeve is inclined or becomes vertical, Is biased to the lower side by the action of gravity.

Therefore, if this is a temporary handling, it is necessary to mount the developing device in an appropriate posture and to drive it for a while so that the developer is evenly distributed.

Therefore, useless waiting time is required.

Further, in the case of continuous use in which the installation orientation of the main body is selected, the unevenness of the developer cannot be eliminated, and the development performance is not constant depending on the installation orientation selection. In some cases, poor development or failure of development may occur.

In the latter publication described above, a screw having a good trapping property of the developer is adopted as a developer carrier in the circulation carrier path for circulating and carrying the developer. However, the portion of the circulation conveyance path facing the developing sleeve is entirely open to a wide space around the developing sleeve.

Therefore, between the screw and the developing sleeve in this portion, a large developer play space is formed in which the developer, which is not exerted by the catching force or the carrying force of the screw and the developing sleeve, can be freely formed. Is biased toward the lower side in accordance with the change in the attitude of the developing device, and the same problem occurs in the above case.

The present invention provides a developing device which can prevent the developer in the developer conveying path from being biased due to the change of the attitude and the direction of the developing device and solve the above-mentioned conventional problems. Is an issue.

[0021]

In order to achieve the above-mentioned object, the present invention has a hopper that stores and supplies a developer, and a developer from the hopper that conveys the developer to a developing field around the photoconductor. After supplying the developer to the developer carrier through the developer supply port in a portion along the developer carrier that forms, a developer transport path for returning the developer by another route and circulating and transporting the developer, A developer transport body provided in the developer transport path for transporting the developer, and the developer transport path is a closed space including the developer carrier together with the developer carrier.
A magnet arranged around the developer play space between the developer carrying body and the developer carrying body in the developer carrying path facing the developer carrying body in the closed space. It is characterized in that the developer is set within a magnetic field range of a strength capable of holding the developer against gravity.

The developer carrier is preferably a screw, and the closed space preferably has an inner surface close to the outer diameter of the screw.

Further, it can be set such that at least a portion of the developer transport path where the developer supply port is provided has an outer diameter inner space of the screw located in the magnetic field.

The magnet may be provided on the developer carrying member, or may be provided on the outer periphery of the developer carrying path for holding the developer.

The developer carrier is made of a magnetic material, and the direction of rotation of the developer carrier, which is opposed to the developer carrier through the developer supply port, is set such that the peripheral surface facing the developer carrier is from the bottom to the top. It is better to move to.

[0026]

According to the above construction of the present invention, the developer from the hopper is circulated by the developer carrier along the developer carrier path containing the developer while the developer carrier is along the developer carrier. Part of the developer can be supplied to the developing field through the developer supply port during the circulating transportation to perform development, and the developer transportation path is a closed space including the developer carrying body and the developer carrying body. Therefore, the developer being circulated and conveyed can be easily trapped in each part during conveyance to regulate free movement, and the developer carrier in the closed space and the surface through the developer supply port The developer play space created between the developer transport path and the developer transport body is set within the magnetic field range of the strength that can hold the developer by the magnets placed around it against gravity. Yes, the developer located in the developer play space is Although it is difficult for the developing sleeve to be caught or carried by the developing sleeve, since the developer has magnetism, it is held against the gravity by the magnetic field and loses its degree of freedom and becomes stable. It is possible to prevent the developer inside from being biased by the influence of gravity.

When the developer transport body is a screw, the developer in the developer transport path can be easily captured, and the closed space formed by the developer transport path has an inner surface close to the outer diameter of the screw. With this configuration, the developer can be easily captured by the developer transport body over the entire closed space, and the free movement of the developer can be regulated to prevent the bias even more advantageously.

If the screw inner diameter space of at least the portion of the developer conveying path where the developer supply port is provided is located within the magnetic field, in addition to the trapping of the developer by the screw. Since the magnetic field is also held by the magnetic field, the bias of the developer can be more surely prevented.

If the developer carrying member has a magnet, it can also serve as a cylindrical magnet built in the developing sleeve.

When the magnet is provided around the outer periphery of the developer transport path and holds the developer, the magnetic field of the developer can be held at any portion.

When the developer transport body is a magnetic body, a magnetic circuit is connected between the magnet and the magnet, and the magnetic field for holding the developer by the limited magnet is likely to reach the entire developer transport path.

When the direction of rotation of the developer carrier, which is opposed to the developer carrier through the developer supply port, is the direction in which the peripheral surface facing the developer carrier moves upward from below, the developer carrier is carried. The developer conveyed by the developer conveying body facing the body is scraped up on the side opposite to the developer carrying body to make it bulky. Therefore, a sufficient amount of developer can be collected on the surface of the developer carrying body with a small amount of developer. Can be contacted with.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention shown in FIGS. 1 to 7 will be described below.

1 to 5 show a developing device, and FIG. 6 shows an image forming device equipped with the developing device. FIG. 7 shows in detail the structure around the photosensitive drum of the image forming apparatus.

This embodiment is a simple, small and inexpensive image forming apparatus particularly suitable for personal use such as being connected to a personal computer. As shown in FIG. The case of a printer having 1 and a print head 2 for performing image exposure on the printer 1 is illustrated.

The print head 2 employs a so-called solid scanning system in which light emitting elements such as LEDs and a liquid crystal shutter are arranged to perform image exposure. Larger models can also employ a printhead that deflects the laser beam to perform scanning.

As shown in FIG.
As shown in FIG. 3, the charging charger 3, the print head 2, the developing device 4, the transfer roller 5, and the cleaning device 6 are sequentially arranged in the rotation direction of the photosensitive drum 1 as indicated by the arrow.

Returning to FIG. 6, in front of the transfer section between the photosensitive drum 1 and the transfer roller 5, a paper feed path 13 is provided which is connected to a manual paper feed port 12 on the outer surface of the main body 11, Behind the transfer section, a fixing device 18 provided in the main body 11
A transport path 15 to is provided.

Behind the fixing device 18, a paper discharge path 17 communicating with the paper discharge port 16 on the outer surface of the main body 11 is provided.

The main body 11 has rectangular side surfaces on the front and rear sides as viewed in a direction perpendicular to the plane of the paper, has two installation surfaces 11a and 11b along one long side and one short side, and the other side has the short side. A mouth 12 and a paper exit 16 are provided. Therefore, installation surface 11
Paper can be fed and discharged regardless of whether the main body 11 is installed by either a or 11b.

Further, with respect to the photosensitive drum 1, the cleaning device 6 is located on the side opposite to the installation surface 11a, and the developing device 4 is located on the installation surface 11a side. The transfer roller 5 is located on the side facing the opening 16.

The paper feed port 12 is provided near the installation surface 11a on the outer surface of the main body 11, and the paper ejection port 16 is provided on the installation surface 11a.
It is provided near the end on the side far from a.

A fixing device 18 is provided at a position apart from the photosensitive drum 1 near the sheet discharge port 16 side between the sheet discharge port 16 and the transfer portion.

As a result, the recording sheet fed from the sheet feeding port 12 is sent to the transfer portion, and after the transfer, the fixing device 18
The sheet can be discharged to the sheet discharge port 16 through the short path using a very small space in the main body 11.

The fixing device 18 is located on the photosensitive drum 1 regardless of which of the installation surfaces 11a and 11b the main body 11 is installed on. Therefore, it is possible to prevent the heat of the fixing device 18 from adversely affecting the image forming mechanism portion around the photosensitive drum 1.

Further, the developing device 4 has the installation surface 11 in view of the above arrangement.
Whether the main body 11 is installed by either a or 11b,
It will be located on the side or below the photosensitive drum 1. For this reason, it is possible to prevent the developer from being excessively supplied due to the gravitational action and clogging the respective parts when the developer is supplied to the photosensitive drum 1 as a developer carrying body to which the developer is directly supplied from the developing device 4. Can be, especially the photosensitive drum 1
It is effective for the developing method of the present embodiment in which the developer is uniformly supplied and adhered to the entire wide area, and then the developer in the non-image area is removed and collected.

In this embodiment, the developer is magnetic.
Although the one-component developer is used, even if the developer leaks from the developing device 4, it is avoided that the developer adheres to the photosensitive drum 1 and stains it.

The paper passage path and the transfer portion of the main body 11 can be opened and closed for jam clearance, repair, and the like. In this case
So that the right side portion of the developing device 4 in is opened,
The developing device 4 and the photosensitive drum 1 which are unitized can be attached and detached through the opening in the direction indicated by an arrow 31 in the figure.

The attaching / detaching direction can be freely set according to the arrangement of other devices and the opening / closing structure of each part of the main body 11.

The developing device 4 itself is shown in detail in FIGS. This will be described. A hopper 21 that stores and supplies the developer, a developer transport path 22 that transports the developer from the hopper 21, and a developer that transports the developer on the developer transport path 22 along the developer transport path 22. Developer carrier 2 that supplies developer to the photosensitive drum 1 as a carrier
4 is provided so that development can be performed in the developing field 23 around the photosensitive drum 1.

The developer transport path 22 includes a forward path 22a for sending the developer from the hopper and a continuous path 22b for returning the developer sent to the forward path 22a to the hopper 21. It forms a circuit. A part of the outward route 22a and the return route 22b, that is, the outward route 22a in this embodiment.
A wide developer supply port 61 is provided at a, which is in contact with the photosensitive drum 1 as the developer carrying member and supplies a sufficient amount of the developer to the entire surface development.

As a result, the water is stored in the hopper 21,
The developer stirred by the stirring blade 20 is sent to the forward path 22a of the developer transport path 22, and then the return path 22 is continued.
Since the returning to the inside of the hopper 21 through b is repeated, a fixed amount of the developer is constantly circulated and conveyed in the circulation path formed by the forward path 22a and the return path 22b of the hopper 21 and the developer conveyance path 22 while the developer is in the hopper 21. It is possible to stably supply the developer to the photosensitive drum 1 as the developer carrying member through the developer supply port 61 during the circulation and conveyance so that proper development can be performed.

In the development of the system in this embodiment, the developer is supplied to a relatively wide area of the photoconductor drum 1 through the wide developer supply port 61, and the image area and the non-image area on the photoconductor drum 1 are exposed. Indiscriminately supplying and attaching the developer to both image parts
It

Next, when the photosensitive drum 1 having the developer adhered to the entire surface reaches the developing field 23, it is detected as the collecting roller 25.
Electric field force and magnetic force due to the potential difference between the photoconductor drum 1 and
The developer adsorbed on the non-image portion on the photosensitive drum 1 is sucked and removed onto the collecting roller 25 by the interaction of the above to complete the development.

When the developer in the non-image area is removed by suction, a DC electric field is applied between the photosensitive drum 1 and the collecting roller 25.
When an alternating electric field is applied to the non-image area, even if the developer is adsorbed on the surface of the non-image area and is stable, the developer particles in the upper layer of the non-image area are relatively free or free and sufficiently free. It is possible to vibrate first to collide it with the stable developer, and effectively suck and remove it toward the collecting roller 25 side.

The developer on the collecting roller 25 removed from the non-image portion is rotated by the collecting roller 25 and the developer conveying path 2
Return to 2 and collect. Reference numeral 52 denotes a blade for collecting the developer, but the developer is supplied to the developer supply port 61 and the collecting roller 2.
It also serves as a seal to prevent leakage from the space between the five.

Further, the developer which is circulated and conveyed returns to the inside of the hopper 21 every time it is circulated, and is renewed and mixed with the developer inside the hopper 21, so that the entire development including the developer inside the hopper 21 is performed. The developer can be supplied while being kept homogeneous, and stable development can be guaranteed without sudden deterioration due to abnormal consumption of some components or uneven distribution of the developer with a long history of use.

Since the forward path 22a and the return path 22b are closed spaces containing the developer transport body 24, the developing device 4 can be used alone or with the main body 11 with the developing device 4 pulled out. Even if the installation direction is changed, the developer in each part in the developer transport path 22 is held in place against the gravity effect between the developer transport body 24 and the developer transport body 24. Also, it is possible to avoid biasing to one side of the return path.

Further, the developer supply port 61, which is in contact with the developer carrying member such as the photosensitive drum 1 of the developer transport path 22, has the forward path 22a.
It is also provided on the photoconductor drum 1 and the collecting roller 25 .
It can be reduced to install bulky along the over La 25.

Further, in this case, if the developer transport path 22 forms the closed space together with the photosensitive drum 1 and the recovery roller 25, the closed space required for supplying the developer to the developing field 23 is narrow. Therefore, the developer can be held more reliably.

The collecting roller 25 is installed in a developing field cover 30a formed integrally with a part of the developing casing 30 forming the hopper 21 and the developer transport path 22.

Further, in the closed space, the developer transport body 24 in the forward path 22a, the photosensitive drum 1 and the collecting roller 25.
The developer play space 55, which is not supported by the conveying force of the developer conveying body 24 and is not supported by the photosensitive drum 1 and the collecting roller 25, is formed in the collecting roller 25 and the photosensitive drum 1. Cylindrical magnet 53 provided in
The magnetic field is formed between the magnetic poles of the sector-shaped magnet 81 and the sector-shaped magnet 81, and is set so as to be located in the magnetic field 54 having a strength capable of holding the developer against gravity.

Therefore, the developer in the developer play space 55 is hard to be caught on the spot without receiving the carrying force of the developer carrying body 24 and the carrying force of the photosensitive drum 1 and the collecting roller 25, but it has a magnetism. If so, the magnetic field 54 holds it against gravity, so that the bias of the developer can be prevented more reliably.

The developer carrying capacity in the developer carrying path 22 is
By increasing the lead of the screw blade 24a of the developer carrier 24, which is a screw, the size is appropriately increased toward the downstream side from the outlet 21a of the hopper 21 to the inlet 21b of the hopper 21 via the forward path 22a and the return path 22b. Is set to.

As a result, a greater conveying force is exerted on the developer sent from the hopper 21 toward the downstream side, and the developer forward path 22a and the developer forward path 22b.
The margin in the inside is gradually increased, and finally, it is sent into the hopper 21 having a large capacity to be released, so that the developer may be clogged during circulatory transfer, and the density becomes close to this, and the development is performed. It is possible to prevent the agent from being strongly fatigued.

If the lead of the developer transport body 24 becomes large, the gripping force of the developer becomes weak, and the developer cannot be sufficiently held in each part, and the bias may not be prevented.

In this case, it is possible to take measures by forming the screw blade 24a in multiple lines.

Further, the width of the connecting path 22c from the outward path 22a to the returning path 22b is made larger than that of the outward path 22a, and the developer being circulated and conveyed is loosened in this portion, so that the next transition in the curved path is made. And transportation becomes smooth.

Further, since the developer carrier 24 in the outward path 22a is a screw and faces the hopper 21, the free developer in the hopper 21 can be well captured and reliably delivered.

The developer carrying capacity of the developer carrying body 24 can be appropriately set by the diameter of the other developer carrying body and the driving speed.

Further, the developer carrying capacity of the hopper outlet 21a is set to be larger than the carrying capacity of the photosensitive drum 1 which is a developer carrier. Therefore, it is possible to prevent the supply amount of the developer from being insufficient to be supplied to the developing field 23 while being circulated and conveyed.

In this embodiment, the lead of the portion of the developer carrying body 24 facing the photosensitive drum 1 is fixed.
As a result, the developer supplied to the photoconductor drum 1 while being circulated and conveyed is different from the photoconductor drum 1 due to the difference in the conveyance speed.
It is possible to prevent the supply amount to the non-uniformity.

When the developer transport body 24 on the return path 22b side has largely entered the hopper 21 as in the present embodiment, the developer is transferred from the return path 22b into the hopper 21 to return the developer to the inside of the hopper 21. It is possible to positively agitate and mix with the developer in the hopper 21 while surely feeding the developer into the inner part of the hopper 21.

Each developer carrier 24 is driven to rotate in the opposite direction by the drive mechanism 82 by the lead of the same direction, and the developer is carried by the meshing of the gears 27 and 28 directly connected to each other. Can be achieved, and the structure of the drive mechanism 82 can be simplified.

Further, this gear connection is performed via the torque limiter 57. Therefore, in the unlikely event of the outward route 22a or the return route 2
Even if excessive addition occurs due to clogging of the developer or high density in 2b, it can be dealt with by the slip of the torque limiter 57,
Avoid excessive driving.

If the developer transport body 24 is a magnetic body,
A magnetic circuit is connected between the magnet 53 and the limited magnet 53.
Therefore, the magnetic field 54 that holds the developer is transferred to the developer transport path 22.
The whole area can be easily made.

Through the developer supply port 61 to the collection roller 25
The rotation direction of the developer transport body 24 facing each other is shown in FIG.
When the main body 11 is stationary on the stationary surface 11a
The peripheral surface facing the collecting roller 25 moves upward from below.
In the moving direction, the toner faces the collecting roller 25.
It is scraped up to the side like the phantom line 72 in the figure.
Since it is higher, you can collect a sufficient amount of developer with less developer.
The surface of the roller 25 can be brought into contact at once.

The screw of the screw which is the developer carrier 24
A special developer scraping member is attached to the crown blade 24a.
There is no need to provide it.

Replenishing port 21 for replenishing the developer of hopper 21
A cover 58 is provided on c, and the developer supply container 43 is attached to remove the cover 58 so that the developer can be supplied.

Since the hopper 21 is located outside one end in the longitudinal direction of the photosensitive drum 1 and the forward path 22a and the return path 22b extend from the hopper 21 in parallel with the photosensitive drum 1, the hopper 21 is located outside the photosensitive drum 1. Not located around the radial surface,
Only the forward path 22a and the backward path 22b of the developer are located around the outer diameter surface of the photosensitive drum 1 in parallel therewith, and the developer can be supplied to the recovery roller 25.
It is possible to halve the space occupied around the photosensitive drum 1.

Therefore, it is advantageous for further downsizing of the image forming section, and there is a space in image exposure, installation of charging means, etc., and the degree of freedom in installation of the image forming device increases. Further, the developing device 4 itself can be installed in any orientation.

Further, in the case where the developing device 4 is unitized with the photosensitive drum 1 or the like and is attached / detached to / from the main body 11 in a lateral direction perpendicular to the axis of the photosensitive drum 1 as shown by an arrow 31 in FIGS. In the case where the hopper is at the back of the developer transport path 22 as described above, the hopper 21 interferes with the print head 2 so that the attachment and detachment cannot be performed.

Therefore, it is conceivable to handle the print head 2 as a unit together with the developing device 4 and the photosensitive drum 1 and simultaneously attach and detach it. However, the print head 2 is expensive and there is a problem in treating it as a consumable item as a part of the detachable unit.

When the hopper 21 is located outside one end in the longitudinal direction of the photosensitive drum 1 as in this embodiment, it does not interfere with the print head 2 in the attachment / detachment, so the print head 2 is used as an element on the main body 11 side. There is an advantage that it can be fixed.

The cleaning device 6 has a cleaning blade 32 in contact with the surface of the photosensitive drum 1, and the cleaning blade 32 removes the residual developer after transfer from the surface of the photosensitive drum 1.

The cleaning blade 32 is provided at one edge of the developer receiving port 34 of the developer returning passage 33 for returning the removed residual developer to the hopper 21, and the removed residual developer is returned to the developer returning passage 33. It is designed to be scooped into. Reference numeral 56 is a seal piece provided on the other edge of the developer receiving port 34.

The developer returning path 33 is provided with a developer carrier 35, which is a screw, and returns the residual developer received in the developer returning path 33 into the hopper 21.
A special device for storing and discarding the residual developer removed by this is unnecessary.

If the image forming apparatus of the present embodiment is of a small size suitable for personal use, the residual developer is collected and used again, but the amount is small and a large amount in the hopper 21. Since it is used by being mixed with the developer of No. 1 by stirring, it is difficult to exert any influence and it does not cause any particular problem.

In this embodiment, the forward path 22a and the backward path 22b of the developer transport path 22 are the forward path 22a facing the photosensitive drum 1 in the installation direction of the main body 11 installed on the installation surface 11a shown in FIG. Is located slightly higher than the return path 22b.

As a result, even when the main body 11 is installed on the installation surface 11b, the positional relationship between the outward path 22a and the return path 22b is constant. Therefore, the supply state of the developer is unlikely to change regardless of whether the main body 11 is installed on the installation surfaces 11a and 11b, and in both cases, the developer is supplied to the photosensitive drum 1 from below. It is advantageous to prevent excessive supply due to gravity.

Therefore, it is possible to prevent the developer from being strongly stressed due to a high density state or clogging due to excessive supply.

It should be noted that the forward path 22a and the return path 22b may be replaced with each other in a positional relationship. As a result, the outward path 22a is on the lower side, so that the developer at the lowest position in the hopper 21 can be sent out and used for development.

The developer carrier 35 is the developer carrier path 22.
Are located in parallel to the developer transport body 24 and close to each other with the photosensitive drum 1 sandwiched therebetween, and can be easily driven by gear-linking and interlocking with them, which contributes to simplification and downsizing of the apparatus. Contribute.

The stirring blade 20 is interlocked with the developer carrier 24 via gears 41 and 42 and is rotated.

With this, without any special drive source or operation,
The developer hopper 21 can be smoothly transferred to the developer transport path 22.

As the developer carrying members 24, 35, various known ones such as those having a carrying blade can be adopted other than the screw.

In particular, as the developer transport body 35, since the developer transport amount is extremely small, a simple one such as a coil spring can be adopted.

FIG. 8 shows a second embodiment of the present invention, in which the developer supply port 61 provided in the outward path 22a of the developer transport path 22 is formed to have a narrow width and development is performed on the development sleeve 27 which is a developer carrying member. It is of a conventional type in which a developing agent is supplied to supply the agent.

The developer supplied to the developing sleeve 27 is regulated in layer thickness by the elastic blade 51, and the developer is charged by friction at this time and is conveyed to the developing field 23. It is sucked into and developed.

The developer in the developer play space 55 can be held against gravity by the magnetic field 54 formed between the magnetic poles of the cylindrical magnet 53 in the developing sleeve 27 .
Reference numeral 50 is a seal piece that seals between the developing field cover 30a and the developing sleeve 27 .

Reference numeral 73 shown in the drawing is outside the developer transport path 22.
Is a magnet for holding the developer, which is provided in this section.
Due to the magnetic field 54 formed, the developer in the developer transport path 22 is
Is held and is free to move.

Since the other structure is the same as that of the first embodiment, the description is omitted.

[0103]

According to the present invention, while the developer from the hopper is circulated and conveyed along the developer conveying path containing the developer by the developer conveying body, the portion of the developer conveying path along the developer carrying body. At, it is possible to perform the development by supplying the developer in the middle of the circulation conveyance to the developing field through the developer supply port,
The developer transport path is a closed space that encloses the developer transport body together with the developer carrier, and it is easy to regulate the free movement by capturing the developer being circulated and transported at each part during transport, A magnet disposed around a developer play space formed in the closed space between the developer carrier and the developer carrier in the developer transport path facing the developer carrier through the developer carrier. The developer located in the developer play space is hard to be caught or carried by the developer carrier and the developing sleeve, because the developer is set within the magnetic field range of the strength capable of holding the developer against gravity. Since the developer has magnetism, it is held against the gravity by the magnetic field and loses its degree of freedom to stabilize, so that the developer in the developer transport path is affected by gravity even if the attitude of the developing device changes. It is possible to prevent the Can have orientation and installation direction is changed without affecting the developing performance, it takes the subsequent break-operation, it is possible to avoid that cause the state of development failure and development impossible.

When the developer transport body is a screw, the developer in the developer transport path can be easily captured, and the closed space formed by the developer transport path has an inner surface close to the outer diameter of the screw. With this configuration, the developer can be easily captured by the developer transporter in the entire closed space, and the free movement of the developer can be regulated to further advantageously prevent the bias and contribute to the stability of the developing performance.

If the inner diameter space of the screw of at least the portion where the developer supply port is provided in the developer transport path is set to be located within the magnetic field, in addition to the trapping of the developer by the screw. Since it is held by the magnetic field, the bias of the developer can be more surely prevented and the developing performance can be further stabilized.

If the developer bearing member has a magnet, it can be used also as a cylindrical magnet or the like built in the developing sleeve, and the structure is not complicated and the cost does not increase.

When the magnet is provided around the outer periphery of the developer conveying path for holding the developer, the magnetic field of the developer can be satisfied at any portion, and the handling orientation or the installation orientation changes. It is possible to achieve the required stable development performance.

When the screw is a magnetic material, a magnetic circuit is connected between the screw and the magnet, and the magnetic field for holding the developer is easily exerted by the limited magnet over the entire conveying path of the developer, so that the developing performance is high and stable. The sex can be easily obtained.

Assuming that the direction of rotation of the developer carrying body, which is opposed to the developer carrying body through the developer supply port, is the direction in which the peripheral surface facing the developer carrying body moves upward from below, the developer carrying body is carried. The developer conveyed by the developer conveying body facing the body is scraped up on the side opposite to the developer carrying body to make it bulky. Therefore, a sufficient amount of developer can be collected on the surface of the developer carrying body with a small amount of developer. Therefore, it is possible to reduce the required amount of the developer to be conveyed and to reduce the size of the apparatus and prevent the developer from fatigue.

[Brief description of drawings]

FIG. 1 is a perspective view of a developing device as a first embodiment to which the present invention is applied.

FIG. 2 is a plan view of the developing device of FIG. 1 as seen in a horizontal cross section.

FIG. 3 is a plan view showing a part of the developing device of FIG. 1 on a hopper side.

FIG. 4 is a sectional view of a hopper portion of the developing device of FIG.

5 is a cross-sectional view of a part of the developing device of FIG. 1 on the hopper side as viewed in a vertical direction.

FIG. 6 is an overall schematic configuration diagram of an image forming apparatus having the developing device of FIG.

7 is a cross-sectional view showing an image forming unit of the image forming apparatus in FIG.

FIG. 8 is a sectional view showing an image forming unit of an image forming apparatus equipped with a developing device as a second embodiment of the present invention.

[Explanation of reference numerals] 1 photoconductor drum 4 developing device 21 hopper 22 developer transport path 22a forward path 22b return path 23 development field 24 developer transport body 27 developing sleeve 53 magnet roller 54 magnetic field 55 developer play space 73 magnet 61 developer supply mouth

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

Claims (7)

[Claims] 1. A hopper that stores and supplies a developer, and a developer that is conveyed from the hopper and is developed on the developer carrier at a portion along the developer carrier that forms a development field around the photoconductor. After the developer is supplied through the developer supply port, the developer is returned through another path to circulate and convey the developer, and a developer provided in the developer conveyance path to convey the developer. And a developer carrier along with the developer carrier, and a closed space containing the developer carrier, and the developer carrier in the closed space and a surface through the developer supply port to the developer carrier. The developer play space between the developer transport body in the developer transport path is set within a magnetic field range of strength that can hold the developer by a magnet arranged around it against gravity. And developing device. 2. The developing device according to claim 1, wherein the developer transport body is a screw, and the closed space has an inner surface close to the outer diameter of the screw. 3. The developing device according to claim 2, wherein at least a portion of the developer transport path where the developer supply port is provided has an outer diameter inner space of the screw located in the magnetic field. . 4. The developing device according to claim 1, wherein the magnet is provided on the developer carrying member. 5. The developing device according to claim 1, wherein the magnet is provided around the outer periphery of the developer transport path for holding the developer. 6. The developer transport body is a magnetic body.
5. The developing device according to any one of 5. 7. The rotation direction of a developer carrying body, which is opposed to the developer carrying body through a developer supply port, is a direction in which a peripheral surface facing the developer carrying body moves upward from below. 7. The developing device according to any one of 1 to 6.